Exact center symmetry and first-order phase transition in QCD with three degenerate dynamical quarks

TL;DR

This study uses lattice simulations to explore the phase transition in three-flavor QCD with an imaginary isospin chemical potential, revealing a first-order deconfinement transition linked to center symmetry.

Contribution

It demonstrates the existence of an exact center symmetry in three-flavor QCD with imaginary isospin chemical potential and characterizes the nature of the deconfinement transition.

Findings

First-order deconfinement transition identified.

Exact center symmetry preserved at low temperatures.

Behavior mapped in the mass-isospin chemical potential plane.

Abstract

We study QCD with three degenerate flavors of dynamical quarks using first-principles lattice simulations. For a specific choice of imaginary isospin chemical potential, this theory possesses an exact center symmetry, just like pure gauge theory. This exact symmetry is expected to be intact at low temperatures and spontaneously broken in the high-temperature regime. By analyzing the finite-size scaling of the Polyakov loop distribution, obtained with a dedicated multi-histogram approach, we demonstrate that there is a first-order deconfinement phase transition in between. Our results are obtained employing stout-smeared rooted staggered quarks at one lattice spacing. Using simulations at different quark masses we sketch the behavior of QCD in the mass-isospin chemical potential plane, shedding new light on this corner of the fundamental phase diagram of the strong interactions and the relationship between chiral symmetry breaking and deconfinement.